15-Minute Workout: Heart-Pumping Circuit

1. Lunge run

Stand with your feet hip-width apart, arms at your sides (a). Step back and lower into a reverse lunge, then pump your arms like you're running for 3-5 seconds, keeping your core tight (b). Press through your front heel to return to standing, then quickly repeat on the other side, continuing alternating.

Do each exercise as a 1-minute interval: do as many reps as you can in 30 seconds, then rest for 30 seconds before continuing to the next move. Rest 1 minute at the end, then repeat the circuit 2 more times. If you're not time-crunched, perform up to 6 intervals for a 30-minute workout.

Beth Bischoff

2. Low-box burpee

Stand facing a box or step with your feet hip-width apart (a). Sit your hips back, bend your knees and place your hands on the step (b), then jump both feet behind you so that your body forms a straight line from head to heels (c). Quickly reverse the movement to return to standing.

4. Primal Push-up

Start in a push-up position (a), then bend your knees and sit your hips back as far as you can, arms straight (b). In one motion, shift your weight onto your hands and drive your right foot forward into a lunge position, raising your right hand off the ground (c). Reverse the movement to return to start, and repeat on the other side; continue alternating.